Hairpin winding electric machine

Abstract

An electric machine includes a stator core defining circumferentially-arranged slots each having radial pin positions arranged to define radial layers and a hairpin winding including a first path of interconnected hairpins disposed in the stator core. The hairpins are arranged such that a leg portion of each hairpin is routed through a radial pin position of each slot wherein at least one uniquely-pitched hairpin is provided along the first path to induce a first shift in a trailing portion of the first path.

What is claimed is: 
     
       1. An electric machine comprising:
 a stator core defining circumferentially-arranged slots each having radial pin positions arranged to define radial layers; and 
 a hairpin winding including a first path of interconnected regular hairpins disposed in the stator core such that a leg portion of each regular hairpin is routed through a radial pin position of each of the slots, wherein each of the regular hairpins has a regular pitch defined by a crown pitch span and two twist pitch spans having same value, wherein at least one uniquely-pitched hairpin is provided along the first path to induce a first shift in a trailing portion of the first path, and wherein the at least one uniquely-pitched hairpin has a unique pitch defined by the crown pitch span, one of the twist pitch spans, and a shorter other twist pitch span having a value less than the same value. 
 
     
     
       2. The electric machine of  claim 1 , wherein the first path of interconnected hairpins corresponds to a first electrical phase and the hairpin winding further includes a second path of interconnected hairpins corresponding to a second electrical phase. 
     
     
       3. The electric machine of  claim 2 , wherein the second path of interconnected hairpins includes at least one uniquely-pitched hairpin along the second path to induce a second shift in a trailing portion of the second path that corresponds to the first shift of the first path. 
     
     
       4. The electric machine of  claim 2 , wherein at least one leg portion of a hairpin of the first path occupies a common slot with at least one leg portion of a hairpin of the second path. 
     
     
       5. The electric machine of  claim 2 , wherein the hairpin winding further includes a third path of interconnected hairpins corresponding to a third electrical phase and each of the first path, second path, and third path are interleaved such that a plurality of slots include leg portions corresponding to at least two of the electrical phases. 
     
     
       6. The electric machine of  claim 5  wherein every other slot of the stator core includes hairpin windings corresponding to a single electrical phase. 
     
     
       7. The electric machine of  claim 5 , wherein each of the first path, second path, and third path includes 16 hairpins with one uniquely-pitched hairpin provided along each respective path. 
     
     
       8. The electric machine of  claim 1 , wherein the first path of the hairpin winding includes a plurality of regular hairpins defining a pitch span of N slots and at least one uniquely-pitched hairpin defining a pitch span of N−1 slots. 
     
     
       9. The electric machine of  claim 1 , wherein the stator core includes forty-eight slots, eight poles, eight radial pin positions within each slot, and four radial layers. 
     
     
       10. An electric machine comprising:
 a stator core defining circumferentially-arranged slots, each slot having radial pin positions arranged in adjacent pairs to define radial layers; and 
 a first electrical phase of a hairpin winding including a plurality of first hairpins interconnected to each other in series around two inner radial layers, and a plurality of second hairpins interconnected to each other in series around two outer radial layers, the second hairpins being connected at a leading edge to the first hairpins via a uniquely-pitched hairpin, wherein the uniquely-pitched hairpin has a unique pitch defined by a crown pitch span, a first twist pitch span, and a second twist pitch span shorter than the first twist pitch span. 
 
     
     
       11. The electric machine of  claim 10 , wherein the uniquely-pitched hairpin induces a first shift in a trailing portion of the first electrical phase of the hairpin winding. 
     
     
       12. The electric machine of  claim 10 , wherein the plurality of first hairpins are regular hairpins defining a pitch span of N slots and the uniquely-pitched hairpin defines a pitch span of N−1 slots due to the shorter second twist pitch span. 
     
     
       13. The electric machine of  claim 10  further comprising a second electrical phase of the hairpin winding interleaved with the first electrical phase such that a plurality of the slots include a hairpin leg portion from both the first and second electrical phases within in a single slot. 
     
     
       14. The electric machine of  claim 13  wherein two inner radial layers of the single slot include a hairpin leg portion from the first electrical phase and two outer radial layers of the single slot include a hairpin leg portion from the second electrical phase. 
     
     
       15. The electric machine of  claim 13  further comprising a third electrical phase of the of the hairpin winding interleaved with the first electrical phase and the second electrical phase such that such that a plurality of slots include hairpin leg portions corresponding to at least two of the electrical phases. 
     
     
       16. The electric machine of  claim 15  wherein every other slot of the stator core includes hairpin windings corresponding to a single electrical phase. 
     
     
       17. An electric machine comprising:
 a stator core defining circumferentially-arranged slots, each slot having radial pin positions arranged in adjacent pairs to define radial layers; 
 a first phase of a hairpin winding having a plurality of first hairpins interconnected to each other in series and positioned in at least one inner radial layer, and a plurality of second hairpins interconnected to each other in series and connected to a trailing edge of the first hairpins by a first unique-pitched hairpin and positioned in at least one outer radial layer, wherein the first uniquely-pitched hairpin has a unique pitch defined by a crown pitch span, a first twist pitch span, and a second twist pitch span shorter than the first twist pitch span; 
 a second phase of the hairpin winding having a plurality of third hairpins interconnected to each other in series and positioned in at least one inner radial layer, and a plurality of fourth hairpins interconnected to each other in series and connected to a trailing edge of the third hairpins by a second unique-pitched hairpin and positioned in at least one outer radial layer; 
 a third phase of the hairpin winding having a plurality of fifth hairpins interconnected to each other in series and positioned in at least one inner radial layer, and a plurality of sixth hairpins interconnected to each other in series and connected to a trailing edge of the fifth hairpins by a third unique-pitched hairpin and positioned in at least one outer radial layer, wherein each of the first phase, the second phase, and the third phase are interleaved such that a plurality of the slots include a hairpin leg portion from both the first and second electrical phases within in a single slot. 
 
     
     
       18. The electric machine of  claim 17  wherein each unique-pitched hairpin induces a shift in a trailing portion of the first phase, the second phase and the third phase. 
     
     
       19. The electric machine of  claim 17  wherein every other slot of the stator core includes hairpin windings corresponding to a single electrical phase.